Disclosure Of Secondary Germline Findings From Clinical Tumor-Normal Paired Somatic Mutation Profiling.

1510Background: Accurate identification of cancer somatic mutations is facilitated by tumor-normal subtractive analysis. Tumor-normal paired testing (TNPT) can also lead to significant secondary germline findings. We report the secondary germline outcomes from clinical TNPT of 4923 patients at a single institution. Methods: TNPT via the Oncomine platform was performed in-house when ordered by patients’ clinicians. Potential secondary germline findings were flagged and sent to clinical cancer genetics (CCG) for review. Pathogenic germline mutations in high penetrance hereditary cancer genes were selected by database and literature review. Medical records were reviewed to determine whether standalone germline testing (SGT) had already identified the mutation. If not, CCG contacted the patient and offered confirmatory SGT via outside reference laboratory. Results: From January 2016 to January 2018, 62/4923 (1.3%) of TNPTs were flagged for CCG review. 41/62 (66%) mutations were selected for follow-up (see tab...